We will present strategies for the fabrication of
novel electrically functional structures from
particles or gels operating in water
environment. In the first part of the talk we will
discuss how electric fields can be used to
assemble metallic or dielectric particles and live
cells into electrical connectors, networks and
sensor prototypes. The structures formed
include microwires from metallic nanoparticles,
crystals with conductive lanes, and
biocomposite membranes from live cells. We
will demonstrate how Janus and patchy
metallodielectric spheres can be assembled in
new types of colloidal crystals and gels and how the type of structures formed can be precisely
controlled by the induced frequency-dependent dipolar and quadrupolar interactions. In the
second part of the talk we will discuss how water-based gels doped with polyelectrolytes can be
used as the core of novel diodes, memristors and photovoltaic cells operating on the conductance
of the counterionic layers around the gel molecular backbone. A new class of “soft” diodes with
rectifying junction formed by interfacing water-based gels doped with polyelectrolytes of
opposite charge was developed. These structures were recently used as a basis of a new class of
memristors, composed entirely of soft and liquid matter by interfacing the gel stacks with liquid
metal electrodes. We also demonstrated a radically new concept of bio-inspired hydrogel solar
cells. The matrix of these photovoltaic cells is made of ionic agarose gels doped with
photosensitive organic molecules. They have open circuit voltages and current density
comparable to polymer photovoltaics. Such gel-based “artificial leaves” can be flexible,
inexpensive and environmentally friendly.

Description:

Presented on February 23, 2011 from 4-5 pm in room G011 of the Molecular Science and Engineering Building.
Runtime: 64:31 minutes